General Contractor License Site Work and Concrete 3 — Questions and Answers
Question 1: What is the purpose of control joints in a concrete slab?
- To allow reinforcement placement
- To create planes of weakness that control cracking location (Correct answer)
- To provide drainage pathways
- To separate the slab from the footing
Correct answer: To create planes of weakness that control cracking location
Control joints are tooled or sawn grooves that create intentional weak planes so that shrinkage cracks occur at planned locations.
Question 2: Soil classified as Type C under OSHA excavation standards is:
- The most stable soil type requiring no shoring
- Granular or fissured soil with the highest risk of collapse (Correct answer)
- Sandy loam with moderate stability
- Rock that can be excavated without blasting
Correct answer: Granular or fissured soil with the highest risk of collapse
Type C is the least stable soil category under OSHA, including granular, fissured, or previously disturbed soils with the greatest collapse risk.
Question 3: The 'angle of repose' for soil refers to:
- The maximum slope at which soil will remain stable without support (Correct answer)
- The bearing capacity of undisturbed soil
- The moisture content at which soil compacts best
- The angle of a footing bearing surface
Correct answer: The maximum slope at which soil will remain stable without support
The angle of repose is the steepest slope at which a particular soil type will naturally stand without sliding or collapsing.
Question 4: Fly ash is commonly used as a partial replacement for Portland cement because it:
- Increases the water demand of the mix
- Improves workability and long-term strength while reducing cost (Correct answer)
- Accelerates the initial set time
- Eliminates the need for curing
Correct answer: Improves workability and long-term strength while reducing cost
Fly ash is a pozzolan that improves workability, reduces heat of hydration, enhances long-term strength, and lowers material costs.
Question 5: What does 'dewatering' mean in the context of excavation work?
- Spraying water to control dust on site
- Removing groundwater from an excavation to keep it dry for construction (Correct answer)
- Testing soil moisture content before compaction
- Washing concrete forms before placement
Correct answer: Removing groundwater from an excavation to keep it dry for construction
Dewatering is the process of pumping or draining groundwater from an excavation to create safe, workable dry conditions.
Question 6: Which of the following is true about isolation joints in concrete construction?
- They must be reinforced with rebar across the joint
- They allow independent movement between adjacent concrete elements (Correct answer)
- They are only used in walls, never in slabs
- They are the same as construction joints
Correct answer: They allow independent movement between adjacent concrete elements
Isolation joints completely separate adjacent concrete elements with a compressible filler to allow differential movement without cracking.
Question 7: A proctor test is used to determine:
- Concrete compressive strength
- Optimum moisture content for maximum soil compaction (Correct answer)
- Soil bearing capacity under load
- Permeability of granular soils
Correct answer: Optimum moisture content for maximum soil compaction
The Proctor compaction test establishes the optimum moisture content at which a specific soil achieves its maximum dry density.
General Contractor License Site Work and Concrete 3
What is the purpose of control joints in a concrete slab?